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1.
The total synthesis of tetrahydroisoquinoline alkaloids (+/-)-renieramycin G (4) and a lemonomycinone analogue (7) is described. A general strategy to synthesize both the mono- and bistetrahydroisoquinoline alkaloids from a common advanced intermediate, 17, is presented. 相似文献
2.
It is shown that the models for highenergy multiparticle production in which the notion of a hadronicformation time plays a central role are in disagreement with recently published compilations of the rescatter probabilities in 100 GeV/c \(\bar p\) d and 200 GeV/c p d collisions. 相似文献
3.
Jun Kawahara Peter Andersson Ersman David Nilsson Kazuya Katoh Yasukazu Nakata Mats Sandberg Marie Nilsson Göran Gustafsson Magnus Berggren 《Journal of Polymer Science.Polymer Physics》2013,51(4):265-271
A flexible electrochromic active matrix addressed display, including 8 × 8 pixels, is demonstrated by using solution processing based on standard printing and coating manufacturing techniques. Each organic electrochromic display (OECD) pixel and its corresponding organic electrochemical transistor (OECT) are located on different sides of the flexible PET substrate. Electronic vias generated through the plastic substrate connects each OECD pixel with one addressing OECT. When comparing this display with actively addressed OECDs with all its components located on the same side, the present approach based on this electronic via substrate provides an enhanced pixel resolution and a relatively more simplified manufacturing process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
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5.
The order within proton pairs in organic molecules, resulting from hydrogenation with parahydrogen, can be transferred in great part to nearby carbon 13 spins through adequate field manipulations. The molecules with hyperpolarized 13C thus obtained can be used as new contrast agents of high efficiency in MRI. After a brief presentation of the hydrogenation process and apparatus, in relatively low magnetic field, we describe the procedure of order transfer to the 13C spins through a sudden drop from the initial field to zero field followed by an adiabatic remagnetization. The expected final polarizations in the absence of relaxation are given for several compounds. Finally, we show an example of MR images observed in vivo on animals as an illustration of the contrast capacity of this new method. 相似文献
6.
Theoretical stability,thin film synthesis and transport properties of the Mon +1GaCn MAX phase 下载免费PDF全文
Rahele Meshkian Arni Sigurdur Ingason Martin Dahlqvist Andrejs Petruhins Unnar B. Arnalds Fridrik Magnus Jun Lu Johanna Rosen 《固体物理学:研究快报》2015,9(3):197-201
The phase stability of Mon +1GaCn has been investigated using ab‐initio calculations. The results indicate stability for the Mo2GaC phase only, with a formation enthalpy of –0.4 meV per atom. Subsequent thin film synthesis of Mo2GaC was performed through magnetron sputtering from elemental targets onto Al2O3 [0001], 6H‐SiC [0001] and MgO [111] substrates within the temperature range of 500 °C and 750 °C. High structural quality films were obtained for synthesis on MgO [111] substrates at 590 ºC. Evaluation of transport properties showed a superconducting behavior with a critical temperature of approximately 7 K, reducing upon the application of an external magnetic field. The results point towards the first superconducting MAX phase in thin film form. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
7.
A model in statistical physics is presented based on assigning non-Abelian phase factors to the turning points of polygons in three dimensions. This model allows for an exact solution and exhibits an unexpectedly rich phase structure. The model as well as the solution are obtained by a generalization of the methods of Kac and Ward and by mapping the problem to a Markov process as was done by Feynman for the two-dimensional Ising model 相似文献
8.
A novel phenomenon is observed in the dynamics of laser-prepared coherent wave packets, bound by the Coulombic 1/r potential of an ion-pair system. After exciting weakly bound (approximately 3 meV) H(+)(-) wave packets in a Stark field, and permitting them to evolve in time, control of field dissociation via adiabatic and diabatic routes is demonstrated by applying delayed pulsed-electric fields, involving a zero-field crossing. Control manifests itself through the production of ions from each pathway at a different instant in time. This phenomenon is applied to map the oscillatory behavior of an angular momentum wave packet in a heavy Rydberg system. The characteristic frequencies of the observed Stark oscillations verify predicted mass-scaling laws for heavy Rydberg systems. 相似文献
9.
Hagslätt H Jönsson B Nydén M Söderman O 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,161(2):138-147
Pulsed field gradient NMR diffusometry is a promising tool for investigating structures of porous material through determinations of dynamic displacements of molecules in porous systems. A problem with this approach is the lack of closed analytical expressions for echo-decays in anything but idealized pore geometries. We present here an approach based on calculating the appropriate diffusion propagator by means of finite element calculations. The suggested method is quite general, and can be applied to arbitrary porous systems. The protocol for the calculations is outlined and we show results from some different cases: diffusion in confined geometries and in systems that are spatially inhomogeneous with respect to concentration. 相似文献
10.
Sverker Fredriksson Magnus Jändel Tomas Larsson 《Zeitschrift fur Physik C Particles and Fields》1982,14(1):35-39
The bulk of data from deep inelasticep, eD, μp, μN, νp and νN scattering is fitted with a new diquark model of nucleons. The proton is found to be mostly in au(ud) 0 state, where the (ud)0 diquark has spin and isospin zero. There is hence no trace ofSU(6) symmetry among diquarks in nucleons. 相似文献